Aleph J-X Amp Project

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BobEllis

BobEllis

Member
Joined 2003
SCAIFF001 said:
Thank you for this detailed comment, I have a better understanding of it but have to read it a few times b4 I can research what you have told me.

How do I bypass the inrush limiter after the surge, a pysical switch ?

I have not ordered a Triac, is it importent, I know nothing about them ?

Thank You for your help, I will recieve the rest of my parts ordered after 06October2010 so I can then assemble my amplifier.
Click to expand...

Those who see a need usually have a relay bypass the triac driven by a time delay (soft start)

Triacs are only needed if you want to use them as a power switch, as done in the A75.


SCAIFF001 said:
Hi Bob, and others("et.al."-Latin for "and others")

I have recieved my soldering iron and filter fan, I purchased a BlackJack SolderWorks BK2000+ soldering station, and Cardas "TRI EUTECTIC ROLL SOLDER". I dont think it is working properly because I have to set the tempiture to 300degree celcius to just hardly melt the solder, which has a melting point of 220degree celcius. I have been practice soldering components on an F5 psu and have to have the iron set to 350degree to attach components to the board, but attached very poorly, 400degree celcius solder iron works well and creates good solder connections between the component and the board.
Is this normal, or do I have either a bad batch of solder, or need to recalabrate my soldering iron, to do this I will have to purchase some sort of thermometer which will probibly be expensive wast of money if the soldering iron is set properly from the factory.
Dose anyone have personal experiance that is consistant with the iron tempitures I have had to use, because many of my components say that I can use a 260degree celcius iron for ten seconds or the component will distroy due to my neglagance with soldering tempitures.

Thank You all for you continued responses, Very Many Thanks.
Click to expand...

No need for recalibrating your temperature setting or thermometer, just crank up the heat until things flow smoothly. The temperature required will depend on the tip size, and the components being soldered. For heavier wires/leads/ traces like a PSU, I use a 2 mm tip and run it up to 425C or more. Remember that those nice heavy copper traces are big heat sinks and will suck a lot of heat out of your tip. The idea is to heat the joint quickly, melt the solder and get out. Tip temperatures too low mean that you'll heat the joint longer, more heat will transfer up the leads and traces and there's more chance that you'll get a cold joint.
 
U

udailey

Member
Joined 2008
picasaweb.google.com/udailey/MyRef#
Also, please consider getting some liquid solder flux. This will make solder flow much faster and end up with beautiful joints. Keep a damp sponge nearby and wipe the solder off of the iron often as it gets dirty and is harder to solder when it is dirty.
Put your iron on the pad you are going to solder but dont touch the part at all with the iron. Let the pad heat up. Put a blob of solder on the iron tip and then when the solder begins to spread out over the pad you roll the iron over to the lead of the component and as soon as wicks up the lead of the component you remove the iron. The pad heating might take a while but if the pad is heated and the solder has started to flow to the pad from the iron it will now only take a second or two to flow up the lead of the component when you roll the iron over to the component.
If you are using a very small solder tip it will take much longer to heat anything and actually may not ever heat enough on some pads and components. Larger parts and traces require a larger soldering iron tip. I use a chisel tip for almost everything. I love it. It holds a lot of heat and makes soldering very fast.
Uriah
 
ggetzoff

ggetzoff

Member
Joined 2004
G

goober5

Member
Joined 2010
Hi Bill and Bob

So I tried again with the other channel using all new parts and a new pair of 2sj74bl matched to 8.78 mA. I'm using the same fets as the last time. I made sure the board is ok before soldering anything. I have the signal ground from R2 and (-) power terminal connected to the safety earth through a CL60.

The output is still 5.0 V (+) relative to the ground. I see that Q5 and 6 run hot where as Q7 and 8 has not heat. I verified that this is not an issue with the FETs by switching the FETs. The voltages are below:
R7 - 4.8V, R8 - 8.3 V, R16 to 19 - 0.5 V.
Vgs Q7 & 8 - 4.2 V and Q5 & 6 - 4.0 V.

I tried shorting the inputs with no change in the voltages. When I tied the (-) input to the ground the output increased to 5.6 V (+) relative to ground.

The output dropped to 0V when I disconnect the ground from R2. But in this case there was 4.5 V between the R2 ground pin and the ground.

Any advise please
Thanks
 
SCAIFF001

SCAIFF001

Member
Joined 2010
soldering a component with no leeds to psb

BobEllis said:
Those who see a need usually have a relay bypass the triac driven by a time delay (soft start)

Triacs are only needed if you want to use them as a power switch, as done in the A75.




No need for recalibrating your temperature setting or thermometer, just crank up the heat until things flow smoothly. The temperature required will depend on the tip size, and the components being soldered. For heavier wires/leads/ traces like a PSU, I use a 2 mm tip and run it up to 425C or more. Remember that those nice heavy copper traces are big heat sinks and will suck a lot of heat out of your tip. The idea is to heat the joint quickly, melt the solder and get out. Tip temperatures too low mean that you'll heat the joint longer, more heat will transfer up the leads and traces and there's more chance that you'll get a cold joint.
Click to expand...

Thank You for this quote, I am following it as directed, I use my largest tip 45degree 4mm at 480 degree(s) heat and then solder getting out of it as quickly as the first solder blob on the iron is sucked into the connection.

I have another problem, I ordered a part not knowing what I was getting into, it is a 3W Resistor R9 to R13 0.47ohms, TYCO ELECTRONICS / CGS - SMW3R47JT - RESISTOR, 3W 5% R47(see parts data sheet below), it has no leeds, do I need to order an other 3watt resistor, or can I mount these onto the board because they are the right size, I only checked the physical size before I ordered this component, I thought it might be a stronger more durable resistor because of the voltage it can handle, I think I have made an expensive mistake because I cannot return these resistors ?

Thank You for your Help

Ian Scaiff(scatterbrain001)
 

Attachments

  • TYCO CGS-SMW3R47JT-RESISTOR 3W R47.pdf
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B

Bill Fuss

RIP
Joined 2005
goober5 said:
Hi Bill and Bob

So I tried again with the other channel using all new parts and a new pair of 2sj74bl matched to 8.78 mA. I'm using the same fets as the last time. I made sure the board is ok before soldering anything. I have the signal ground from R2 and (-) power terminal connected to the safety earth through a CL60.

The output is still 5.0 V (+) relative to the ground. I see that Q5 and 6 run hot where as Q7 and 8 has not heat. I verified that this is not an issue with the FETs by switching the FETs. The voltages are below:
R7 - 4.8V, R8 - 8.3 V, R16 to 19 - 0.5 V.
Vgs Q7 & 8 - 4.2 V and Q5 & 6 - 4.0 V.

I tried shorting the inputs with no change in the voltages. When I tied the (-) input to the ground the output increased to 5.6 V (+) relative to ground.

The output dropped to 0V when I disconnect the ground from R2. But in this case there was 4.5 V between the R2 ground pin and the ground.

Any advise please
Thanks
Click to expand...

Hi Goober,

The safety ground should not be an issue unless you have somehow wired the CL60 into the signal ground path. If you have directly grounded the PS to the chassis please remove it.

Please check the drop across R18-19 again. If Q7-8 are not conducting there cannot be voltage across them.

Maybe a couple pics would help.
 
G

goober5

Member
Joined 2010
Hi Bill

Attached is a link to pictures of my set up. I have Q5-8 off board until I get this thing working and figure out an enclosure. All the cables to Q5-8 are of equal lengths and 16 gauge. I also loaded a sketch of the way every thing is hooked up.

Picasa Web Albums - umesh a - alephj

I verified the voltages in R18 and 19 and they are the same (pic 2). There is some heat load in Q7 and 8 but it's much less and takes a long while to feel. Out of curiosity I measured the voltage at the Drain of Q7-8 relative to ground and it was 5 V where as Q5-6 was around 21 V.

Thanks for the help
 
SCAIFF001

SCAIFF001

Member
Joined 2010
R9 to R13 values

SCAIFF001 said:
Thank You for this quote, I am following it as directed, I use my largest tip 45degree 4mm at 480 degree(s) heat and then solder getting out of it as quickly as the first solder blob on the iron is sucked into the connection.

I have another problem, I ordered a part not knowing what I was getting into, it is a 3W Resistor R9 to R13 0.47ohms, TYCO ELECTRONICS / CGS - SMW3R47JT - RESISTOR, 3W 5% R47(see parts data sheet below), it has no leeds, do I need to order an other 3watt resistor, or can I mount these onto the board because they are the right size, I only checked the physical size before I ordered this component, I thought it might be a stronger more durable resistor because of the voltage it can handle, I think I have made an expensive mistake because I cannot return these resistors ?

Hi Bob & Bill

I think I have to order another resistor for R9 to R13, I believe I could add a leed to each end of the resistors I have purchased already made from the pieces trimmed of of the other mounted components.
Is matching values for these R9 to R13 more important than getting the value of 0.47ohms, I have found there are many 1% 3watt resistors for 0.5ohms, how important is it that I follow the exact resistance of these resistors because 1% resistors will match each other much better than 5%
resistors.

Thank You for your help
Thank You for your Help

Ian Scaiff(scatterbrain001)
Click to expand...
 
SCAIFF001

SCAIFF001

Member
Joined 2010
R9 to R13 are matching these resistors more importent than exact value of 0.47ohms

Hi Bob & Bill

I think I have to order another resistor for R9 to R13, I believe I could add a leed to each end of the resistors I have purchased already made from the pieces trimmed of of the other mounted components.
Is matching values for these R9 to R13 more important than getting the value of 0.47ohms, I have found there are many 1% 3watt resistors for 0.5ohms, how important is it that I follow the exact resistance of these resistors because 1% resistors will match each other much better than 5%
resistors.

Thank You for your Help

Ian Scaiff(scatterbrain001)
 

Attachments

  • www.ohmite.com - 40_series 33R 3W 1%.pdf
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A

Alettagla

Member
Joined 2008
Beginners question,

Some time ago I ordered the aleph jx pcb's
Im now collecting parts as cheap as possible from everywere .

I got offered some transformers each transformer is rated as follows:

2x18v 500va (two complete separate secundair windings capable of delivering 13,5 amp each)
Size 13,cm x 6,5 cm weight circa 4,5 kg

Wil one of these be sufficient for one mono channel aleph-jx?

I would think this is enough because the original aleph-j uses one 300va transformer for two (stereo) channels.

Your advise is most welcome
 
SCAIFF001

SCAIFF001

Member
Joined 2010
matching MOSFETs

BobEllis said:
Ian,

3W should be OK since they only see about .75W, but it wouldn't hurt to parallel 2x 1R. I wouldn't try to add leads to the SMD resistors you found. Matched resistors is ideal, at least within each group. It's not terribly critical, though. 1% should be fine.
Click to expand...

I have read that the problem with testing Power MOSFETs is that the DMM Bench Power Supply is expensive, I am considering useing one of the following for a bench power supply to use with a DMM and hook cables, or pincer, cables: http://triadmagnetics.com/pdf/page 11.pdf
24Volt 1050mAmp constant current:
TRIAD MAGNETICS|TLD1040-24-C1050|POWER SUPPLY, SWITCH MODE, 24V | Newark Canada
24Volt 350mAmp constant current:
TRIAD MAGNETICS|TLD1020-24-C0350|POWER SUPPLY, SWITCH MODE, 24V | Newark Canada
24Volt 1670mAmp constant voltage:
TRIAD MAGNETICS|TLD1040-24|POWER SUPPLY, SWITCH MODE, 24V | Newark Canada

I dont know which one would be the best to use for the matching MOSFETs, and dose anyone know what is a good Digital Multi Meter to purchase, I was sent a cheep one as a gift for puchasing over $50.00 of stuff and I can not get any meaningfull numbers off of it, either it is me or the DMM is crap? Am I approaching this matching MOSFETs correctly ?

Thank You for all of your help

Ian
 
BobEllis

BobEllis

Member
Joined 2003
Do you have your power supply parts? You won't need all the caps for matching, but why buy a power supply just for matching? Just adjust the resistor in your matching rig to allow for approximately your planned bias current.

What do you mean by "can not get any meaningful numbers off of it"? For matching purposes you need consistency, the actual number matters little. Use clip leads if supplied with your meter, if not buy some and clip to the leads. Wiggling hands can change things. Ensure that your leads are well seated in the meter.

Measure a 9V and 1.5V battery each several times. How close do you to the same voltage do you get each time?

Fluke is the gold standard if you need to buy another meter, but expect to spend over $200. Anything over $30 or so should do.
 
Bksabath

Bksabath

Banned
Joined 2007
Hi Ian
I am going trough the process of building my first Nelson design.
A Lm317 is enough to do the Job for me for the suply.

What count is your meter the one I have has a 4000 count and I can get the 2nd Decimal place.

I have noticed that numbers changes with the temperature.
Have a look at the tread I have started and came back to me If you need more help

Al
 
ggetzoff

ggetzoff

Member
Joined 2004
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